Mowers having a plurality of rotary cutting blades that rotate in substantially horizontal cutting planes are well known for cutting grass. The blades in such a multi-bladed mower are typically carried on a large cutting deck that is coupled to a traction frame of some type. The traction frame often comprises part of a vehicle that carries a seated or standing operator. Mowers of this type are particularly well suited for mowing large areas of grass because of the use of a riding vehicle to carry the cutting deck as well as the large size of the cutting deck.
Multi-bladed cutting decks are often designed to discharge the grass clippings created by the blades through a common exit tunnel. For example, in a cutting deck having two side-by-side cutting blades, the blades are often rotated in opposite directions. The grass clippings generated by each blade are directed towards the center of the deck and merge with each other to form a stream of grass clippings that are projected rearwardly on the deck along the center of the deck. A rear discharge opening is provided at the rear and the center of the deck for receiving this stream of grass clippings and for discharging the grass clippings from the deck. The rear discharge opening is formed by the open mouth of a rearwardly extending exit tunnel through which the grass clippings pass as they discharge from the deck.
The exit tunnel that carries the grass clippings is often connected to some type of grass bagger or collector for collecting the clippings and for preventing the clippings from being discharged onto the ground. However, when such a collector is used, it must be manually dumped or emptied when it becomes filled. This requires the operator to stop mowing, to drive the mower to some area where the clippings can be dumped, and to then dump the clippings by pivoting the collector on the mower in a dumping operation or otherwise removing the collector. Once the collector is emptied, the operator can then drive back to where he or she had stopped mowing to resume mowing.
The collectors often used on mowers of this type necessarily have a somewhat limited capacity due to the additional weight the mower is required to carry as the collector fills. Use of counterweights for stability reasons imposes an additional weight penalty that the mower must carry. As a practical matter, mower mounted grass collectors are relatively small in size in comparison with the volume of grass clippings that can be produced by the action of multiple cutting blades.
Consequently, when a grass collector is used to collect the grass clippings from a multi-bladed cutting deck, the collector will often have to be emptied quite frequently. This interrupts the mowing operation as noted above The need to break away from mowing at frequent intervals to go dump the grass clippings reduces the productivity of such mowers.
Cutting decks of this type can be converted into a mulching mode by closing off the exit tunnel in some fashion. The grass clippings are thus prevented from being discharged from the deck but instead circulate around the various cutting chambers until they are discharged or fall out of the open bottom face of the cutting chambers. However, since the clippings from the multiple blades are merged into a single rearwardly directed stream of clippings, the deck tends to discharge the clippings in somewhat of a central windrow. This is not optimal mulching performance since the windrow containing the grass clippings will at least be partially visible on top of the cut grass path. It would be an advance in the art if the grass clippings were better distributed on the surface of the cut grass path when the deck is converted into a mulching mode.
In addition, mowers of this type are converted between the mulching mode and the discharge/collection mode of operation in an all or nothing manner. In other words, the deck is either used for mulching or it is used to discharge the grass clippings onto the ground or into a grass collector. Other than for choosing between one of these two modes, the operator has little control over how quickly the grass clippings pass out of the cutting deck in the discharge/collection mode of operation. It would be another advance in the art to give the operator some way to adjust how quickly the grass collector fills.